Remote controlling apparatus



Aug. 23, 1938. L v, w s 2,127,691

REMOTE CONTROLLING APPARATUS Filed June 25, 1929 4 Sheets-Sheet l Line to-Szazions D! D l'l l'l l- 0R our Aug. 23, 1938. L, v. LEWIS 2,127,691

REMOTE CONTROLLING APPARATUS Filed June 25, 1929 4 Sheets-Sheet 2 I 1' CA a CA 4 c v 0 c 0H2 0H5 0H4 0H5 0H6 OH? 0178 0H9 OHIO OHIZ pm/yanks,

5 each station and at the office.

Patented Aug. 23, 1938 UNITED STATES REMOTE CONTROLLING APPARATUS Lloyd V. Lewis, Edgewood, Pa., assignor to The Union Switch & Signal Company swissvale, Pa., a corporation of Pennsylvania Application June 25, 1929, Serial No. 373,675

100 Claims.

My invention relates to remote controlling apparatus, and particularly to apparatus adapted to be used in a centralized traffic control system for railroads, for controlling a plurality of train governing devices, such as railway switches or signals, from a remote point, such for example, as a train despatchers oflice, and for also indieating the condition of such devices at said .office.

The apparatus of my invention, as herein disclosed, is an improvement upon the apparatus shown and claimed in my copending applications, Serial No. 254,690, filed Feb. 16, 1928, for Railway trafic controlling apparatus, and Serial No. 291,465, filed July 9, 1928, for Remote controlling apparatus, the subject matter of said latter application being shown by British Patent 315,220 accepted October 6, 1930.

I will describe one form of apparatus embody- 120 ing my invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Figs. 1 and 2, when placed side by side with Fig. 1 on the left, form a diagrammatic View illustrating a portion of a train despatchers oflice provided with apparatus embodying my invention. Figs.

3 and 4 when placed side by side with Fig. 3

on the left, form a diagrammatic View showing a remote station suitable for co-operation with the apparatusillustrated in Figs. 1 and 2 and also embodying my invention.

Similar reference characters refer to similar parts in each of the several views.

-In the modern operation of railway systems it is sometimes desirable to control a number of trafiic governing devices located at spaced points over a considerable stretch of track from a central point, such as a despatchers office, and also to indicate at the control-office, the condition of -;,40 each of these devices. The traflic governing devices are here illustrated as switches and signals,

' each switch with the corresponding complement of trackway signals being considered as one station, and a plurality of stations being controlled 146 from the despatchers oflice indicated in the drawings on Figs. 1 and 2. The despatchers office and all of the remote stations, are connected together by means of a normally closed line circuit including two line wires DI and D2 so which extend throughout the system. The line circuit is normally supplied with energy from a line battery N located at the despatchers office, and under normal conditions, the line circuit is closed through the winding of a line relay at Each line relay is designated by the reference character R with a prefix corresponding to the location. A transmitting relay is provided for each station and the despatchers ofiice, and a master relay is also provided for each station and for the despatch- 5 ers oflice. Each transmitting relay is designated by the reference character T, and each master relay is designated by the reference character M, with appropriate prefixes referring to the location. Each master relay M is con- .10 trolled, as will beexplained hereinafter, in such manner that the relay is normally de-energized and is arranged to be energized only when a code originating in the apparatus associated with such master relay is being transmitted'over the line 15 circuit. At each remote station, the line circuit' includes a back contact of the master relay and when the associated master relay is energized, the portion of the line beyond that station is disconnected and the line circuit is completed go to the despatchersofiice'over a back contact of the corresponding transmitting relay. At the despatchers ofiice, the line circuit does not include a contact of the master relay, but passes directly over a back contact of the transmitting 25 relay.

The control of the various parts is accomplished by means of code signals transmitted ,or long interval of time and again closing the line circuit for a short. interval. The first impulse ss of each code is a locking impulse, the function of which will be described hereinafter. Certain of the impulses following the locking impulse in each code are used to select the station or the corresponding panel at the ofiice, the number, 4 of such station or panel selecting impulses required for this purpose depending upon the numberof stations to be controlled from the despatchers office. In illustrating my invention, I have assumed that twelve stations are to be controlled from the despatchers ofiice, and with this arrangement, seven station selecting impulses are required. The next impulses in each code are used to select the particular operations to be performed at-the selectedstation or panel,

and with the apparatus here illustrated I require four impulses for this purpose in control codes originating at the despatchers. office for controlling apparatus at the several stations In indication codes originating at the station for informing the operator at the ofiice of the condition of apparatus at the station's, seven impulses are necessary to select the particular operations.

The last impulse of each code accomplishes the operation of the devices at the selected station or panel, and also restores the apparatus to normal to prepare it for the reception or transmission of additional codes. With the arrangement here illustrated, therefore, each control code originating at the despatchers oifice contains thirteen impulses, and each indication code originating at a remote station contains sixteen impulses, certain of which are prolonged to accomplish different purposes as will appear hereinafter.

For purposes of simplicity, I have illustrated only one remote station complete in the drawings, and have shown only that portion of the despatchers ofiice equipment necessary for the control and indication of this one station, but it will be understood, of course, that the other eleven stations are similar to station No. 1, here illustrated, and that the additional equipment required at the despatchers ofiice will simply duplicate a portion of the equipment here shown.

Referring now particularly to Fig. 4, there is located at station No. l a stretch of railway track, the rails of which are designated by the reference characters I and I These rails are divided, by means of insulated joints 2, to form a track section b This section is provided with a switch 3 of the usual form communicating with a siding 1'. The track rails adjacent the section b-f are divided to form a plurality of approach track sections ab, oL-e and fg. The main track section b-f, and each approach track section is provided with a source of track circuit current, such as a battery 4, connected across the rails adjacent one end of the section, and a track relay connected across the rails adjacent the other end of the section. The track relay for the section containing the switch 3 is designated ITR and the track relay for approach section a--b is designated IRA. Relays ILBA and ILAA are the track relays for approach sections d-e and fg, respectively.

Eastbound traflic over the switch 3 is controlled by two signals IRA and IRB, which as here shown are mounted upon the samemast, and Westbound traific over the switch 3 is controlled by signals ILB and ILA. The signals may be of any suitable form, and as here shown are of the usual semaphore type.

The switch 3 operates a plurality of circuit controllers I, 8, 9 and I which are arranged to assume one position or another in response to the position of switch 3 in accordance with usual practice. Switch 3 is in turn controlled by a motor m comprising an armature 32 and a field 34. It is also desirable to arrange the motor for manual operation and for this' purpose the switch is provided with what is known as adual selector mechanism forming no part of my present invention and not shown in the drawings, but comprising two contacts and 6' which are normally closed, and which are arranged to be opened whenv the dual selector mechanism is placed in condition for manual operation of the switch. The motor m is controlled in part by two route selecting stick relays INWS and IRWS which'are controlled as will be explained hereinafter in accordance with control codes received from the despatchersbifice. Associated with the track relay ITR is a track repeater relay ITP, the circuit of which includes contact 5 of the dual selector mechanism of switch 3 and front contact II of track relay ITR. The

repeater relay ITP is therefore deenergized when section b is occupied or when the switch 3 is under manual control.

The signals at station No. l are controlled in part by two traflic direction controlling stick relays ILH and IRH, responsive to control codes received from the despatchers office as will be explained hereinafter. The two traffic direction controlling relays ILH and I RH control a plurality of signal control relays, one for each signal, and each designated by a reference character formed by adding H to the reference character for the corresponding signal.

The reference character IX designates a back lock relay which is energized only when all of the signals governing traffic over switch 3 are at stop. The circuit for this relay may be traced from terminal B of a source not shown in the drawings,

through contact 2! operated by signal IRB, contact 22 operated by signal IRA, contact 23 operated by signal ILA, contact 24 operated by signal ILB, and winding of relay IX, back to terminal C of the same source.

' Station No. 1 is also provided with a locking relay IV which is controlled in part by the track relays of the approach sections and in part by a manually operable key release It. The relay IV is normally energized over a stick circuit which may be traced from terminal B, over front contact I3 of relay ILBA, front contact I4 of relay ILAA, front contact I5 of relay IRA, front contact I6 of relay IV and winding of relay IV to terminal C. Back contact'I'I of signal control relay ILBH is connected in parallel with front contact I3 of relay ILBA, back contact I8 of signal control relay ILAH is connected in parallel with front contact IQ of relay ILAA, and back contacts 20 and I9 of signal control relays IRAH and IRBH, respectively, are connected in series across front contact I5 of relay IRA. It is plain, therefore, that the stick circuit for relay IV is normally closed, but that if a train enters any of the approach sections leading into section bf, the opening of the corresponding approach relay will break the stick circuit for relay IV, provided the corresponding signal control relay is energized to clear the appropriate signal. After relay IV has once become de-energized, it can be picked up by the de-energization of relay ITR, whereupon, current is supplied to relay IV, over back contact I2 of relay I TR, or the key release k may be operated to supply current to relay IV over a reverse contact 5!] of the key release 70. The control of relay IV is in accordance with standard practice for the control of approach locking relays in systems of the type here contemplated, and the operation of this relay will be apparent from the drawings without further explanation.

For the actual control of switch motor m, two electromagnetic contactors I NW and IRW are controlled by the relays INWS and IRWS. As shown in the'drawings, the switch 3 occupies its normal position, and relay INWS is energized. In explaining the operation of the switch motor, I will assume that relay I NWS becomes de-energized and relay IRWS becomes energized. When this happens, front contact 28 of relay IRWS becomes closed. The contactor IRW is provided with a circuit which may be traced from terminal B, over front contact 25 of relay IX, front contact 26 of relay IV, front contact 21 of relay ITP, front contact 28 of relay IRWS, contact 8-8 operated by switch 3, and Winding of contactor IRW to terminal C. It will be plain that the contactor IRW can not become energized unless all signals are at stop, the approach locking is released, and the main track section b--,f is unoccupied. When contactor IRW becomes energized, current flows from terminal B, through heater 29 of a thermo-sensitive relay hl, front contact 3| of contactor IRW, armature 32 of motor m, front contact 33 of contactor IRW, field 34 of motor m, and contact 6 of the dual selector mechanism of switch 3 to terminal C. The motor m is then operated to move the switch to its reverse position. When the switch attains its full reverse position, the opening of contact 88 interrupts the circuit for contactor IRW and de-energizes motor m. In similar manner, the switch 3 may be restored to its normal position by energizing relay INWS. The circuit for contactor INW passes from terminal B, over front contact 25 of relay IX, front contact 26 of relay lV, front contact 21 of relay ITP, front contact 35 of relay INWS, contact operated by switch J, and winding of contactor INW to terminal C. When contactor INW becomes energized, current flows from terminal B, through heater 29 of thermo-sensitive relay 712, front contact 36 of contactor INW, armature 32 of motor 111., front contact 31 of contactor INW, field 34 of motor m, and contact 6 on the dual selector mechanism of switch 3 to terminal C. When the motor m is energized over the circuit just traced, the motor is operated to drive the switch 3 to its normal position. When the switch has attained its full normal position, theopening of contact 1-4 interrupts the circuit for contactor l NW, which therefore opens its front contacts to de-energize motor m. The purpose of thermo-sensitive relays hl and M will be described hereinafter.

The reference character IKR designates a switch indication relay which is controlled jointly by the relays lNWS and IRWS, and by contacts actuated directly by the'switch 3. The indication relay IKR is a polarized relay and with the parts occupying the positions in which they are illustrated in the drawings, current flows from terminal B, over back contact 33 of relay IRWS, front contact 39 of relay INWS, contact 9---9 operated by switch 3, winding of relay IKR, and contact Ill-lll operated by switch 3 to terminal C. The current supplied to relay IKE, under these conditions, energizes the relay in its normal'direction so that its polar contacts are swung to the left. If relay lRWShas been energized to move the switch to its reverse position, the circuit for relay IKR will then pass from terminal B, over back contact 39 of relay INWS, front contact 38 of relay IRWS, contact Ill-Ni winding of relay IE3, and contact 99 to terminal C. The current then supplied to relay IKR will energize the relay in its reverse direction so that the polar contacts of the relay will be swung to the right. It should be pointed out, however, that if the switch control relays INWS and IRWS are both de-energized simultaneously, or if the position of the switch does not correspond with the condition of the switch control relays, the indication relay IKR will be de-energized.

The signal control relays lLAI-I, ILBH, IRAH and FREE are controlled jointly by the trafiic direction controlling stick relays lLI-I and IRH and by the switch indication relay lKR. For example, when relay ILH is energized to permit traffic moves from east to west, front contact 46 of this relay is closed, and if the switch 3 is then normal so that relay [KR is energized in the normal direction, current flows from terminal B, over front contact 40 of relay lLI-I, front contact 4| of indication relay IKR, normal contact 42 of indication relay IKR and winding of relay ILAI-I to terminal C. When relay ILAI-I is energized, current is supplied to the operating mechanism of signal ILA, over front contact 43 of relay ILAI-I so that signal ILA is then cleared to permit westbound trafiic to pass over the switch in its normal position. If, however, the switch 3 is reversed when relay ILH becomes energized, the indication relay IKR is reversed, and relay ELBH is then energized over front contact 43 of relay ILH and front contact 4| and reverse contact42 of relay IKR. The closing of front contact 44 of relay ILBH completes a circuit for-the operating mechanism of signal ILB which signal is then cleared to permit westbound traffic to proceed over switch 3 in its reverse position. In similar manner, when relay IRH is energized, and indication relay iKR is energized in its normal direction, relay IRAH is energized over front contact 45 of relay IRI-I,

and front contact 48 and normal contact 41 of relay IKR, and when relay lRAI-I is energized, current is supplied over front contact 48 of this relay to operate the signal IRA to its clear position. Finally, if relay IKR is energized in its reverse position when relay IRH is energized, relay IRBH is picked up over front contact 45 of relay iRI-I and front contact 36 and reverse contact 41' of relay IKR. Current is then supplied over front contact 49 of relay lRBI-I to clear signal IRB. It should be noted that if relays ILH and lRI-I are both de-energized, all signals will be at stop. Furthermore, all signals are put to stop by the de-energization of relay iKR as a result of any of the conditions previously mentioned in describing the control circuit for this relay, or by this opening of front contact I92 of track relay In actual practice, the signals may be semiautomatic that is to say, they may be moved only from their stop positions to their caution positions by the apparatus herein shown and described, and may then move automatically from caution to clear under control of traffic conditions in the territory adjacent the portion of track shown in the drawings.

The route stick relays INWS and IRWS and the traflic' direction stick relays lLII and lRI-I are controlled by two manually operable levers Ip and Iq located on a suitable panel at the despatchers ofiice, as shown in Fig. 2. This panel is individual to station No. l and in addition to the two control levers is provided with a plurality of indication lamps by means of which the condition of the apparatus at station No. l is indicated. Of course, a similar panel is provided for each of the other stations. The control panel for each station is also provided with a starting button each designated by the reference character OP with a suffix corresponding to the panel. Associated with each main panel is also an approach panel which is provided with an indication lamp for giving visual information concerning the condition of certain apparatus not conveyed by indication apparatus on the main control panel.

As stated above, the codes delivered to the line circuit are made up of impulses formed by briefly opening the circuit. Since the line relays R at the office and at each remote station are all included in series in the line circuit, each such impulse causes each line relay to become de-energized, and when the line circuit is again closed, the line relays all become energized. Each line relay controls a chain of counting relays here shown as seven in number and each designated by the reference character B with a distinguishing prefix corresponding to the location and with a suffix corresponding to its position in the chain. Referring particularly to the apparatus shown in Fig. 1, line relay OR controls a chain of counting relays OBI, OBIa, etc. The alternate relays of the chain, identified by the sufiixes 2, 3, and 4, control the various circuits for transmitting and receiving the successive code elements, while the intervening relays, identified by the suffixes Ia, 2a, etc., are transfer relays which operate during the intervals between code elements. Each line relay also controls a second chain of counting relays also seven in number and each designated by the reference character C with a prefix corresponding to the location and a sufiix designating the position in the chain. The purpose of the second counting chain is to enable the B relays of the first chain to be employed repeatedly, thereby decreasing the total number of counting relays required. The alternate relays of the second chain, identified by the suffixes I, 2, etc., are group relays, one being energized for each cycle of operation of the relays of the first chain, while the remaining relays of the second chain, identified by the sufiixes la, 20., etc, are transfer relays which operate during the intervals between the cycles of operation of the relays of the first chain. The relays of the second counting chain are controlled by the associated line relay in such manner that in response to repeated operation of the line relay the relays of the B chain are first energized and de-energized successively with relay OCI energized, and the B relays are then successively energized and de-energized a second time with relay C2 energized, and the same operation is repeated with relays 003 and CO4. Associated with each set of counting relays are three slow-releasing relays designated by the reference characters K, J and Ka, with prefixes corresponding to the location. At the despatchers olfice, an additional slow releasing relay OJP is also provided.

The operation of the system depends to some extent upon the time required for the operations of certain relays and for purposes of explanation I have assumed definite values for certain parts, but it should be understood that these values are not essential, but are mentioned only by way of illustration. It is desired that the parts should operate as rapidly as possible and for measuring the intervals required for certain functions the ordinary unit of one second is too long to be convenient. For purposes of reference, therefore, it is convenient to measure these time intervals by referring them to cycles of alternating current of commercial frequency, such as 60 cycles per second. With this explanation in mind, I shall assume that the pick-up times for all relays are substantially the same and equal approximately one cycle of alternating current of a frequency of 60 cycles per second. For convenience in manufacture, I propose to construct the relays with similar parts and to adjust the release times of certain relays by variation in the air gaps and by connecting asymmetric units in parallel with the relays. These asymmetric units are each designated by the reference character a: and it will be seen that asymmetric units are connected in parallel with certain ones of the relays, as for example, relays OK and OJ at the despatchers plies to the line relays R. The transmitting relays T, the master relays M, and the counting relays B and C release in 4 cycles while relays OJ and OK at the office and all relays K at the stations have release times of approximately 12 cycles. Relay OKa at the ofiice has a release time of 16 cycles. Relays J at the several stations have longer release times than the corresponding relay OJ at the ofiice, and I will assume that the release times of the station relays J are 16 cycles. The relays Ka at the stations also have slower releasing characteristics than relay OKa at the office, the relays Ka at the stations being assumed to release in 20 cycles. Relay OJP at the ofiice has a release time of 8 cycles.

As will be described in detail hereinafter the normal length of each impulse of .each code, that is, the interval during which the line circuit is open, is approximately 8 cycles and successive impulses are separated by intervals also of approximately 8 cycles during which the line circuit is closed. Under certain conditions, however, some of the impulses in each code are prolonged as will be explained in detail as the description proceeds. With these preliminary remarks in mind, I will now describe the operation of the counting relays at the despatchers oflice in response to a code in the line circuit.

Under normal conditions, all counting relays are de-energized and relays OK, OJ, OJP and OKa are also de-energized. Relay OR, is of course, energized, because the line circuit is normally closed. The first impulse of the code deenergizes relay OR, thereby closing back contact and completing a pick-up circuit for relay OCI, over back contact 5| of relay OR, and back contact 53 of relay OK. Relay OCI therefore becomes energized. The de-energization of relay OR also completes a pick-up circuit for relay OJ, over back contact 5| of relay OR and back contact 52 of relay OK. When relay OJ becomes energized, a circuit is completed over back contact 5| of relay OR, contact 54-54 of relay OK and front contact 55 of relay OJ, to energize relay OBI. When relay OBI picks up, a circuit is completed for relay OK, over back contact 5| of relay OR, contact 5454 of relay OK, front contact 55 of relay OJ, front contact 59 of relay OBI, and front contact I6 of relay OCI. Relay OK therefore becomes energized, whereupon the pick-up circuit just traced is opened, but relay OK is now stuck up over back contact 5| of relay OR and its own front contact 5454 When relay OK becomes energized, the circuit previously traced for relay OJ is also interrupted but relay OJ, having a release time of 12 cycles, does not immediately release. When relay OK closes its front contact 53, a stick circuit is completed for relay OBI, over back contact 5| of relay OR, front contact 53 of relay OK, and front contact 59 of relay OBI. The energization of relay OK also closes a stick circuit for relay OCI, over front contact 56 of relay OK, back contact III of relay OCI a, and front contact 60 of relay OCI. When relay OCI picked up, it completed a circuit for relay OJP over back contact 5| of relay OR, back contact 53 of relay OK, front contact 60 of relay OCI, back contact 69 of relay COM, and front contact 51 of relay OJ, and relay OJP picked up at the same time as relay OBI. When relay OJP possible unless the relays operate successively and picked up, its front contact 58 connected relay OKa in parallel with relay OJP, and relay OKa therefor picked up at the same time as relay OK.

After relay OK has closed its front contact,

battery is supplied to relays OJP and OKa over front contact 51 of relay OJ and front contact 56 of relay OK to hold the latter relays enere gized until OK releases.

The operation of relays OJP and OKa just described has no particular significance in relation to the operation of the chains of counting relays now being described and is only mentioned in passing. Under some conditions, the first impulse of the code may be prolonged so that relay OJ becomes de-energized but this operation also is unrelated to the operation of the counting relays and further reference will be had to it as the description proceeds.

At the end of the first impulse, relay OR again becomes energized, thereby opening back contact 5| and closing front contact 5|. The stick circuit for relay OK is now open at back contact 5| of relay OR but relay OK is sufiiciently slowacting to bridge the comparatively brief intervals of energization of relay OR which never exceeded 8 cycles, so that relay OK remains closed until the code has been completed. When relay OR becomes energized, a circuit is completed for relay OJ over front contact 5| of relay OR, and front contact 52 of relay OK, and it will therefore be seen that relay OJ is energized during each interval between successive impulses in a code supplied to the line circuit. The energization of relay OR interrupted the stick circuit for relay OBI, but has no effect upon relay OCI which is now held up over front contact 56 of relay OK, back contact 10 of relay OCIa, and front contact 60 of relay OCI. Relay OBI is therefore tie-energized, but before this relay opens its front contacts, a pick-up circuit is completed for relay OBIa, over front contact 5| of relay OR, front contact 6| of relay OK and front contact 62 of relay OBI. Relay OBIa therefore becomes energized and is subsequently stuck up over front contact 5| of relay OR, front contact 6| of relay OK, and front contact 63 of relay OBIa. After the expiration of its brief holding interval, relay OBI releases.

When relay OR becomes de-energized at the beginning of the second impulse in a code, current is again supplied to relay OK, and the holding circuit for relay OJ opens. Relay OJ remains energized, however, unless the second impulse is prolonged. The de-energization of relay OR also completes a pick-up circuit for relay 0B2 over back contact 5| of relay OR, front contact 53 of relay OK, back contact 59 of relay OBI, and front contact 64 of relay OBIa. The stick circuit for relay OBIa is now open at front contact 5| of relay OR and relay OBIa becomes de-energized. Relay 0B2 is now held up, however, by virtue of its stick circuit over back contact 5| of relay OR, front contact 53 of rela; OK, and front contact 65 of relay 0B2. 7

The operation of the remaining relays B in the counting chain is similar to that just described for relays OBI, 03111 and 0B2, it being noticed that each energization and de-energization of relay OR picks up a succeeding relay B in the chain and de-energizes the preceding relay. It should also be noted that the pick-up circuit for each counting relay includes a front contact of the preceding relay in the chain and a back contact of the second preceding relay in the chain so that operation of the counting chain is imin order.

' The operation of the relays continues until relayv OR'becomes energized at the expiration of the fourth impulse of the code. When this happens, Jthe' stick circuit for relay 0B4, now energized, is interrupted, but before relay 0134 releases, a pick-up circuit is closed for relay OCIa, over front contact 5| of relay OR, front contact 6| of relay OK, back contact I56v of relay 0330., front contact 61 of relay 0B4, and front contact 8801 relay OCI. Relay OCIa therefore becomes energized and after relay 0134v releases, relay OCia is held up over a stick circuit including front .contact 5| of relay OR, front contact 6| of relay OK, andfront contact 69 of relayOCIa. When relay. OR next becomes de-energized, at the. beginning of the fifth impulse, relay OBI becomes energized over back contact 5| of relay OR, front contact v53. of relay OK, back contact s20 2990f relay DB4, and front contact ll of relay OCIa Furthermore, when relay OCIa became energized, .thestick circuit for relay OCI was opened at back contact 10 of relay OCIa so that relay OCI released and closed its back contact 68 to complete a pick-up circuit for rel-ay 0C2 over front contact 56 of relay OK, back contact 6|) of ,relay OCI, and front contact III of relay OCIa.

Relay 0C2 therefore picks up and closes its stick circuit over front contact 56 of relay OK, back contact 12 of relay COM and front cont-act H of relay. 0C2. During the fifth impulse, then, relay CO2 is energized and relay OBI is energized. -Relay 0C2 remains energized as the relays of the B chain are successively energized ,35

by the fifth, sixth, seventh and eighth impulses inthe-same manner as described in connection with the successive operation of these relays in response to the first four impulses of a code. In similar manner, the ninth impulse commences the successive operation of the counting relays of the-B chain for the third time, and during the energization of these relays in response to the ninth, tenth, eleventh and twelfth impulses, relay 003 is energized. The thirteenth impulse of a code, picks up relays OBI and CO4 and if the code contains sixteen impulses, the fourteenth, fifteenth and sixteenth impulses energize relays 0B2, DB3 and 034 in succession,

while relay OC4 remains energized. The final impulse of every code ,is prolonged and during this prolonged impulse, relays OJ, OJP and OKa become de-energized in succession. When relay OR becomes energized after this final impulse,

howevenrelaysOJ, OJP and OKa again become energized in succession. Relay OR now remains steadily energized, so. that relay OK is de-energized. At the expiration of the holding time of approximately 1 2 cycles, relay OK releases. The opening of' the front contacts of relay K deenergizes'relays OJ, OJP, OKa and any of the counting relays-B or C which may happen to-be energized. The apparatus is therefore restored to its normal condition.

'Itshou ld bepointed out that relay OJ is en- 'ergize'd during "the intervals between successive impulses of a code, but is de-energized during each impulse. If any impulse exceeds the holding time of relay OJ of approximately 12 cycles,

energized during the short impulses of a code but release in succession during each prolonged,

scribed hereinafter.

It should also be pointed out that if relay OR becomes energized during the reception of a code for a longer time than the release time of relay OK, this relay will release, thereby breaking the stick circuit for any counting relay which may happen to be energized and also releasing relays OJ, OJP and OKa. This operation restores the counting chains to their original condition and prevents operation of any function due to an incorrect code or an accidental interruption in the line circuit.

The operation of the counting relays at each station in response to operation of the associated line relay is similar to the operation just described in connection with the despatchers oflice with the single exception that the station equipment does not include the repeater relay OJP, but relay Ka at each station is controlled directly over a front contact of the corresponding relay J. In all other respects the station equipment is identical with the ofiice equipment and the operation will be understood without tracing it in detail.

In addition to the apparatus previously described, the despatchers office is provided with three lock-out relays OLI, 0L2, and 0L3 and with three group selector relays OGI, 0G2 and 0G3. Furthermore, the office is provided with a station relay and a starting relay for each panel. Each station relay is designated by the reference character OS and each starting relay by the reference character OH, with sufiixes corresponding to the panel with which such relay is identified. The ofiice equipment also includes a series of register or indication storing relays OFI to OFT, inclusive, and a delivery relay OF8, while the apparatus of each office panel includes a series of indication relays ONWI, ORWI, ORTI, ORAI, OLHI, and ORHI.

In explaining the operation of the apparatus, I will assume that all parts occupy the positions in which they are shown in the drawings, that is, all sections of track at station No. 1 are unoccupied, so that all approach and track relays are energized, repeater relay I'IP is energized, switch 3' occupies its normal position and signal ILA is cleared to permit westbound moves over the switch 3. At the despatchers office, the apparatus associated with panel No. 1 corresponds in condition with the devices at station No. 1. The indicationrelay ONWI, is energized by virtue of a stick circuit which may be traced from terminal B, over back contact Hi--18 of station relay OSI (now de-energized) back contact I9 of starting relay OHI (now de-energized) and front contact Bl] of relay ONWI. Relay OLI-II is also energized, its stick circuit passing from terminal B, through back contact 18-18 of relay OSI, front contact 8| of relay OLHI, and winding of relay OLHI to terminal C.

The indication lamps on the several panels are supplied with energy in any suitable manner. As here shown, these lamps are at times supplied with alternating current from busses 82 and 83 which are connected with the secondary of transformer t when the power-off relay w is energized. The relay w is connected across the secondary of transformer 15, the primary of which is constantly supplied with alternating current not shown in the drawings. Under ordinary conditions, therefore, the buses 82 and 83, receive alternating current for the control of the panel lamps, but if for any reason the supply of alter- 'several remote stations.

impulse. The functions of these relays will be denating current should fail, relay 111 would become de-energized and the busses 82 and 83 would then be connected with terminals B and C of an auxiliary source of energy. Circuits for the track indication lamp 8'! of panel No. 1 and track indication lamp 86 of the approach panel are open so that these lamps are de-energized. The switch normal indication lamp 88 is connected with busses 82 and 83 over front contact 84 of relay ONWI, so that this lamp is lighted to indicate that the switch 3 at station No. l occupies its normal position in accordance with the position of the switch control lever Ip on panel No. 1. In similar manner, the left-hand signal clear indication lamp 90 is connected with busses 82 and 83 over front contact 85 of relay OLI-II so that this lamp is lighted to indicate that a westboundsignal at station No. 1 is clear in accordance with the position of the signal control lever Iq. Since the operator knows that the switch occupies its normal position, he can infer that the signal which is clear is ILA which governs traific over the switch in its normal position. All other lamps on panel No. 1 are extinguished.

Furthermore, all other relays at the despatchers office are de-energized with the exception of relay OR which is, of course, energized because it is included in the normally closed line circuit.

I Will now assume that the operator wishes to reverse switch 3 at station No. 1 and also to clear a, signal IRB to authorize traffic movements from noted that back contact I9 of relay OH! is included in the stick circuit for relay ONWI and since the starting relay OHI. is now energized,

Them

"relay ONi/VI releases, thereby opening the circuit for lamp 88 at front contact 84 of relay ONWI, and extinguishing this lamp. The lamp 90 however, remains lighted. Relay OI-II controls a circuit for the master relay OM at the despatchers ofiice which circuit may be traced from terminal B, over front contact 93 of relay OHI, back contact 94 of relay 0B2, back contact 95 of relay OK, back contact 96 of relay OKa, and winding of relay OM to terminal C.

over back contact 91 of relay OBI, back contact 98 of relay 0B2, back contact 99 of relay 0B3, back contact I00 of relay 0134, front contact II]! of relay OM, and winding of relay OT to terminal '0. Relay OT therefore becomes energized and interrupts the line circuit at back contact I02 of relay OT. This operation of relay OT starts 'the first impulse of a control code and of course de-energizes the line relay OR at the despatchers oifice and also de-energizes all relays R at the The de-energization of relay OR sets the counting chains B and C into operation in the manner previously described, that is to say, relays OJ, OCI, OBI, OK, OJP and OKa become energized. When relay OK becomes energized the lock-out relay OLI is energized over a circuit which may be traced from terminal B, over front contact 56 of relay OK, front contact I03 of relay OBI, front contact I04 of relay OCI, and winding of relay OLI to terminal C. Relay OLI. is subsequently stuck up over a circuit which may be traced from terminal B, over front contact 56 of relay OK, front contact I05 of relay OKa, back contact I06 of relay 004, back contact IIlI of relay 0L3, back contact IUScf relay 0L2, front contact I09 of relay OLI and winding of relay OLI to terminal C. Relay OLI is therefore picked up and stuck up during the first impulse of the control code.

When relay OK became energized the pick-up circuit previously traced for relay OM was opened at back contact 95 of relay OK but relay OM is now held in its energized condition over a stick circuit which was closed when relay OKa. became energized and which may be traced from terminal B, over front contact of relay OK, front contact III] of relay OM, front contact 96 of relay OKa and winding of relay OM to terminal C. The circuit previously traced for relay OT over back contacts of the counting relays OBI, 0B2, etc., was interrupted at back contact 91 of relay OBI when the latter relay became energized, but a holding circuit was completed for relay OT when relay OJP became energized and this circuit passes from terminal B, over front contact 9'! of relay OBI, front contact III of relay OCI, front contact II2 of relay OJP, front contact H3 of relay OT, front contact IIJI of relay OM, and winding of relay OT to terminal C. It should also be noticed that when relay OK became energized the circuit was interrupted for relay OJ, and when relay OJ releases, the circuit for relay OJP is interrupted. When relay OJP releases, the stick circuit just traced for relay OT is interrupted at front contact H2. of relay OJP, and relay OT is then de-energized to close theline circuit and terminate the first impulse. It will be clear from the foregoing that during the first impulse, the line circuit was held open for a time interval equal to the sum of the release times of relays OJ, OJP and OT.

When relay OT becomes de-energized at the conclusion of the first impulse, relay OR becomes energized and picks up relay OBIa as previously described. Relay OBI is also de-energized, and when this relay closes its back contact 91 the circuit is again completed to pick up relay OT and initiate the second impulse. The energization of relay OT opens the line circuit, thus causing relay OR to become de-energized. Relay OBZ is then energized and is subsequently stuck up over its own front contact as explained hereinbefore. When relay 0B2 picks up it opens the normal circuit for relay OT at back contact 98 of relay 0B2, but a holding circuit for relay OT is now closed from terminal B, over front contact 93 of relay OHI, front contact 94 of relay 0B2, front contact H4 of relay OLI front contact II3 of relay OT, front contact ll of relay OM, and winding of relay OT to terminal C. Relay OT therefore remains energized, until relay OLI releases, to prolong the second impulse. This prolonged impulse allows relays OJ and OJP to release in succession and when relay OJP releases, a pick-up circuit is completed for one of the group selector relays and energizes relay OGI its back contact over a circuit which passes from terminal B, over front contact 56 of relay OK, front contact H5 of relay OKa, back contact H6 of relay OJ, back contact II! of relay OJP, front contact I I8 of relay 0B2, front contact II9 of relay OLI, front contact I20 of relay OCI and winding of relay OGI to terminal C. Relay OGI therefore becomes energized and when this occurs, current flows over the circuit just traced as far as front contact I20 of relay OCI and thence over front contact I2! of relay OGI, and winding of relay 0L2 to terminal C. Relays OGI and 0L2 therefore pick up in succession. The energization of relay 0L2 opens the stick circuit for relay OLI, which thereupon becomes de-energized. Relay 0L2 remains energized by virtue of a stick circuit which passes from terminal B, over front contact 55 of relay OK, front contact I05 of relay OKa, back contact I06 of relay 0C4, back contact ID! of relay 0L3, front contact I08 of relay 0L2, and winding of relay 0L2 to terminal C. Current also flows over the stick circuit just traced as far as front contact I08 of relay 0L2 and thence through front contact IZI of relay OGI and winding of relay OGI to terminal C. Relays 0L2 and OGI are therefore held in their energized condition. When relay OLI releases, the holding circuit for relay OT is interrupted at front contact II 4 of relay OLI, and relay OT becomes deenergized to terminate'the second impulse.

When back contact I02 of relay OT closes, the line circuit is again completed and relay OR becomes energized. When front contact 5I of relay OR closes, relay OB2a becomes energized and is subsequently stuck up over its own front contact. Relay 032 is now de-energized and when this relay releases, the closing of its back contact 98 completes the pick-up circuit for relay OT to start the'third impulse.

It should be observed that when relay OR became energized, relays OJ and OJP were again energized over front contacts of relay OK and a front contact of relay OR. At the beginning of the third impulse caused by energization of relay OT, relay OR again becomes de-energized and picks up relay 0B3. Relay OBZa, of course, becomes de-energized and releases. The energization of relay 0B3 interrupts the pickup circuit for relay OT, and since there is no holding circuit now closed for relay OT, this relay again releases and terminates the third impulse which is therefore short.

The releasing of relay OT again picks up relay OR, and when this occurs relay OBSa picks up and sticks over its own front contact. Relay 0B3 then releases and closes the pick-up circuit for relay OT at back contact 99 of relay 0B3. As a result, relay OT again becomes energized and interrupts the line circuit and tie-energizes relay OR to start the fourth impulse. When relay OR becomes de-energized at the beginning of the fourth impulse, relay 0B4 becomes energized and is subsequently stuck up over its own front contact. Relay OB3a then releases. The energization of relay 0B4 interrupts the pick-up circuit for relay OT at back contact I00 of relay 034, and since no holding circuit is now completed for relay OT, that relay releases, and when I02 closes, the line circuit is again closed to pick up relay OR and terminate the fourth impulse.

The energization of relay OR closes the pickup circuit for relay OCIa over front contacts 6'! and 68 of relays 0-134 and OCI relay OCIa becomes energized. The opening of back contact I0 of relay OCIa interrupts the stick circuit for relay OCI, which latter relay now releases. When relay 0C! closes its back contact 60, relay 0C2 becomes energized as described hereinbefore, and is subsequently stuck up over its own front contact II and back contact I2 of relay OCZ'a. When relay 0B4 becomes de-energized following the energization of relay OR, the pick-up circuit for relay OT is again closed and this relay becomes energized to open the line circuit to start the fifth impulse.

When relay OR becomes de-energized, the closing of back contact 5! picks up relay OBI, which subsequently sticks up over its front contact 59. This operation of relay OBI interrupts the pickup circuit for relay OT, but relay OT is now held up over a circuit which may be traced from terminal B over front contact 290 of relay OGI, front contact I24 of relay OHI, front contact I25 of relay OBI, front contact 526 of relay 0C2, front contact I I3 of relay OT, front contact I0! of relay OM, and Winding of relay OT to terminal C.

Relay OT is therefore held energized until relay OGI becomes deenergized, thereby prolonging the fifth impulse. This longimpulse will allow relays OJ and OJP to release sucessively, and when this occurs a pick-up circuit is completed for relay OS! from terminal'B, over front contact 55 of relay OK, front contact H5 of relay OKa, back contact I I6 of relay OJ, back contact I l! of relay OJP, front contact I2! of relay OBI, front contact I28 of relay 0C2, front contact I29 of relay OGI, and winding of relay OS! to terminal C. When relay OS! becomes energized, current flows over its pick-up circuit just traced as far as front contact I29 of relay- OGI, and thence over front contact !30 of relay OSI,back contact I3! of relay OF8 (now closed) and winding of relay 0L3 to terminal C. Relay 0L3 therefore becomes energized and breaks the stick circuits for relays 0L2 and OGI. Relay 0L3 is now stuck up over a circuit which may be traced from terminal B, over front contact 56 of relay OK, front contact I05 of relay OKa, back contact I05 of relay 0C4, front contact Nil of relay 0L3, back contact I3I of relay OF8 and winding of relayOL3 to terminal C. A stick circuit is also completed for relay OSI which is the same as the stick circuit just traced for relay 0L3 as far as front contact iii? of relay 0L3, passing thence over front contact I30 of relay OSI, and winding of relay OS! to terminal C. The release of relay 0G! interrupted the holding circuit for relay OT, and relay OT now releases to terminate the fifth impulse which has been prolonged as just described.

It should be noted that when relay OGI releases, it interrupts the holding circuits controlled by relays OH2, CH3 and 01-10, thereby making it impossible for starting relays associated with other panels to interfere with the control of the code now being delivered which originated at panel No. 1. Furthermore, the de-energization of relay OGI interrupts the pick-up circuits for relays 0S2, OS3 and 08 so that no additional station selector relays at thedespatchers office may be energized. Relays O6! and 0L2 are, of course, now de-energized. It should also be pointed out that when relay OSI became energized, the stick circuit for relay OH I was opened, so that relay OH! now releases. the operation of relay OS! interrupts the stick circuit previously traced for relay OLHI over back contact 78-78 of relay OSI. A holding circuit is now completed, however, for relay OLHI from Furthermore,

terminal B, over front contact I32 of relay OM, front contact Ill-J8 of relay OSI, and front contact 8! of relay OLHI and winding of relay OLHI to terminal C. Relay OLI-II therefore remains energized and lamp on panel No. 1 remains lighted.

When relay OT becomes de-energized, following the opening of relay 0G! and closing of its back contact I02, restores the line circuit, so that relay OR becomes energized, to terminate the fifth impulse. The energization of relay OR picks up relay 03m, and then relay OBI releases to close its back contacts and energize relay OT to start thesixth impulse. This operation of relay OT lie-energizes relay OR which picks up relay 032 to open the circuit for relay OT and relay OBIa, of course, releases. The opening of the pick-up circuit for relay OT at back contact 98 of relay 0B2 releases relay OT, because no holding circuit is now completed for this, relay. When relay OT closes its back contact I02, the line circuit is again closed to terminate the sixth impulse and pick up relay OR. This operation of relay OR energizes relay 032a and releases. relay 0B2. When back contact 98 of relay 0B2 becomes closed the pick-up circuit is completed for relay OT and that relay becomes energized to open the line circuit and start the seventh impulse. When relay OR becomes deenergized at the beginning of the seventh impulse, relay 0B3 becomes energized and relay OB2a releases. The energization of relay 0B3 interrupts the pick-up circuit for relay OT, and since there is now no holding circuit for this relay, relay OT releases to close the line circuit and terminate the seventh impulse. Relay OR therefore becomes energized and picks up relay OB3a and releases relay 033. When back contact 99 of relay 0B3 closes, the pick-up circuit is completed for relay OT and this relay opens its back contact I02 to interrupt the line circuit and start the eighth impulse. When relay OR becomes de-energized, relay 0B4 picks up and relay OB3a releases. 0B4 interrupts the pick-up circuit for relay OT and since no holding circuit is completed for this relay it closes its back contact and restores the line circuit to terminate the eighth impulse. The closing of line relay OR picks up relay OCZa, and the latter relay opens its back contact 72 in the stick circuit for relay 0C2, thereby releasing relay 002. When relay 0C2 closes its back contact II, relay 0C3 becomes energized over its pickup circuit including contact 56 of relay OK, back contact II of relay 002 and front contact I2 of relay OC2a, and relay 003 is then held energized over its stick circuit including its own front contact l3 and back contact 14 of relay 0C3a. Relay 0B4 then releases, and when back contact I00 of relay 0B4 becomes closed the pick-up circuit is completed for relay OT to energize this relay and open the line circuit to start the ninth impulse. Relay OR then becomes de-energized and picks up relay OBI, thereby interrupting the corcuit for relay OT at back contact 97 of relay OBI, and releasing relay OCZa. Relay OT then releases and restores the line circuit to terminate the ninth impulse. When relay OR becomes energized, relay OBIa picks up and relay OBI becomes de-energized, thereby again restoring the pick-up circuit for relay OT and breaking the line circuit to start the tenth impulse. When relay OR becomes de-energized, relay 032 is picked up and relay OBIa releases. The energization of relay 0B2 interrupts the pick-up circuit The energization of relay for relay OT at back contact 98 of relay 0B2 but relay OT is now held energized over a circuit which maybe traced from terminal B, over back contact 91' of relay OBI, front contact 98 of relay 0B2, switch control lever Ip on panel No. 1 in its reverse or right-hand position, front contact 295 of relay OSI, front contact I33 of relay 003, front contact H2 of relay OJP, front contact II3 of relay OT, front contact IIII of relay OM, and

winding of relay OT to terminal C. Relay OT is held energized by the circuit just traced to prolong. the tenth impulse. During this long impulse, relays OJ and OJP release successively and when. relay OJP releases, the opening of front contact II2 of relay OJP interrupts the holding circuit for relay OT and permits that relay to release and restore the line circuit to terminate the tenth impulse. The relay OR then becomes energized, picking .up relays OJ and OJP and also relay 0B2a. Relay 0B2 then releases and restores the normalpick-up circuit for relay OT to open the line circuit and start the eleventh impulse. Relay OR then becomes de-energized, picking up relay 033 and releasing relay 0133a. The energization of relay 0B3 breaks the pickup circuit for relay OT and since there is no holding circuit for relay OT, under these conditions, relay OT releases to terminate the eleventh impulse. The relay OR then picks up, energizing relay 033a, and releases relay 0B3, closing the pick-up circuit for relay OT. When the latter relay becomes energized, the line circuit is opened to start the twelfth impulse. When relay OR becomes de-energized, relay 0B4 picks up and relay OB3a releases. The energization of relay 0B4 opens the pick-up circuit for relay OT, but this relay is now held energized over a circuit from terminal B, through back contact 91 of relay OBI, back contact 98 of relay 032, back contact 99 of relay 0B3, front contact I00 of relay 0B4, signal control lever Iq on panel No. l in its reverse or right-hand position, front contact I34 of relay OSI front contact I33 of relay 003, front contact II2 of relay OJP, front contact I I3 of relay OT, front contact IOI of relay OM and winding of relay OT to terminal C. Relay OT therefore holds the line circuit open to prolong the twelfth impulse. During this long impulse, relays OJ and OJP release successively and when relay OJP opens its front contact II2, the holding circuit for relay OT is interrupted. When relay OT closes its back contact I02, the line circuit is restored to terminate the twelfth impulse. Relay OR therefore picks up and relay 0030, becomes energized and. opens its back contact 14 to release relay 0C3. When relay 0C3 releases, the pickup circuit for relay 004 is closed over front contact 56 of relay OK, back contact I3 of relay 0C3 and front contact 14 of relay OC3a so that relay 0C4 becomes energized. Relay 004 is then held energized over its stick circuit including its own front contact I5 and front contact 56 of relay OK until relay OK releases at the end of the code. Relay'OB l then releases and when back contact I00 .of this relay becomes closed, a pick-up circuit is again completed for' relay OT to start the thirteenth impulse. Relays OJ and OJP became energized when relay OR picked up. At the start of the thirteenth impulse, relay OR becomes deenergized, thereby picking up relay OBI and releasing relay 003a. The thirteenth impulse is the final or delivery impulse of the control code and this impulse is longer than any other. impulse in the controlcode. The pick-up circuit forrelay OT is, of course interrupted: as soon as relay OBI picks .up-but a holding circuit for relay OT is-nowzclosed fromterminal B,.:over front contact 91 of relay OBI, front contact I35 of relay 0C4, front contact N3 of relay OT, front contact IIII ofrelay OM, and winding of relay OT to terminal C. Itshould be noted that when relay 004 becomes. energ-ized it breaks the stick circuits for relays 0L3 and OSI at back contact I06 of relay 0C4. During this thirteenth impulse, relay OJ becomes de-energized and when this relay releases, relay OJP becomes de-energized. When relay OJP releases, it opens thecircuit for relay OKa, which then releases and interrupts the holding circuit for relay OM. When relay OM releases, it opens the holding circuit for relay OT and-allows relay OT toclose its back contact I02 and .restore the line circuit to terminate the thirteenth impulse. When relay OR becomes energized-,relays OJ, OJP and OKa again become energized, relay OBIa also picks up and relay OBI releases. Relay OM does not become energized, however,.and the release of relay OBI does notpick up relay OT, because the pick-up circuit for relay OT is'now open at front contact IUI of relay OM. The line circuit,.therefore, remains closed,.relay OR remainssteadily energized and after a brief interval, relay OK releases. When relay OK releases, it. de-energizes relays OJ, OJP, OKa, OBIa and CO4. It should be noted that as soon'as relays OK and OKa have released successively, ,-thez.pick-up circuit for relay OM is again prepared so that the operation of a push button on one of the control panels will immediately start the transmission of another control code. If no push button is operated, however, it will be apparent, that'all of the relays remain deenergizedexceptrelay; OR and relay OLHI. With: reference to the latter relay, it will be observed that. the sticky circuit for the relay was restored to the back contact 'I8I8 of relay OSI at. the conclusion of the control code. After the controlilcode has been'transmitted tothe line circuit,,then, and before the reception of a correspondingindication code, lamp 90 on panel No.

1 continuesto burn but all. other lamps are extinguished.

- It will .be'. observed that relay OI-II is provided with an auxiliary stickcircuit including its own fronttconta'ct I23,,front contact I22-I 22 of relay OSI, and backcontact I32 of relay M. The purpose ofthis auxiliary stick circuitis to maintain relay OHI energized after operation. of push button ,OPI, while; an indication code is being received atpanelNo; 1. detail hereinafter, relay OSI is energized under these. conditions, but. the. stick circuit just traced holds-relayOHI energized so that the. apparatus remains. in-=condition-to transmit a control code after the indication code is completed.

- -In.the foregoing"explanation,.I have described the. operation of the apparatus at the despatchers ,ofiicezin. transmitting acontrolcode to the line circuit, and it ,will be seen that this control code consists of thirteen impulses, the first,second, fifth-,itenth, twelfthand thirteenth of which are As will be explained in long, xrWhllB the remaining are shortimpulses.

.Thejfi-rstor locking impulse is prolonged by the successive releases of relays. OJ, OJP and OT relays OJ, OJP, OGI, L2, OLI and CT, while impulse is determined by the consecutive releases of relays OJ, OJP, 0L3, 0L2 and OT. Each of impulses 2 and 5 are substantially 30 cycles long. The tenth and twelfth impulses are function selecting impulses and each is approximately 28 cycles long, being determined by the consecutive releases of relays OJ, OJP and OT. The thirteenth or final impulse of the control code is determined by the consecutive releases of relays OJ, OJP, OKa, OM and OT, this final impulse is substantially 45 cycles long.

I will now describe the operation of the apparatus at station No. 1, in response to the control code thus transmitted over the line circuit. It should be kept in mind that the operation of the apparatus at the remaining stations is similar in all respects to the operation of the apparatus at station No. 1 except that the several stations are selectively responsive to the location in the control code of the second and third long impulses, and only station No. 1 will be responsive to the particular code just described.

In addition to the relays previously described, station No. 1 is provided with a lock-out relay L, a group selector relay IG, a station selector relay IS, and a series of register relays IFI to IF I and a delivery relay IF5. Furthermore, the station is provided with a plurality of relays II-ID, ITD, ITK, IAD, IAK and IHK which are utilized for starting purposes when the apparatus at the station is operating to transmit a code to the line circuit.

As shown in the drawings (Fig. 4) the route stick relay INWS is stuck up over a circuit which may be traced from terminal B, over contact 5 operated by dual selector mechanism of switch 3, normal contact I64 of key release is, back contact I69 of register relay IF5, front contact I86 of relay INWS and contact 36 of thermo-sensitive relay h2 to terminal C. The switch occupies its normal position so that the indication relay IKR is energized. The trafiic direction stick relay I Ll-I is also energized, the stick circuit forthis relay passing from terminal B, through contact 5 of the dual selector mechanism of switch 3, normal contact I64 of key release It, back contact I'M of relay IF5, back contact I80 of relay IRH, front contact I19 of relay ILH, winding of relay ILH toterminal C. Since relay ILH is energized and relay IKR is energized in the normal direction, relay I LAH isenergized and signal ILA is clear. Relay IX is therefore deenergized, this relay being energized as previously explained only when the signals at station No. 1 are all at stop.

The counting relay chains IBI, IBIa, etc., and ICI, ICIa, etc., are controlled in precisely the same manner as the corresponding counting chains discussed in connection with the despatchers office and illustrated in Fig. 1. When the first impulse of the control code transmitted from the despatchers oflice is transmitted to the line circuit, the line relay at each station becomes de-energized but these relays subsequently follow. the code supplied to the line circuit. When relay IR at station No. 1 first becomes deenergized, relays IJ, ICI, IBI, IKa and IK become energized as will be understood from the drawings without tracing the circuits for these relays in detail. When relay IK picks up, the circuit for relay IJ is interrupted and since the first impulse of a control code is long, relay IJ opens at the expiration of its release period. It will be remembered that the locking impulse of the control code is approximately 28 cycles long and that the release time of relay IJ at station No. 1 is approximately 16 cycles, and it follows that after relay IJ releases, there is a brief interval of time during which relay IJ is open and before relay IR again becomes energized to pick up relay IJ. During this brief interval, a pick-up circuit is completed for a lock-out relay at each remote station. At station No. 1 this pick-up circuit may be tracedfrom terminal B, over front contact 296 of relay IK, frontcontact I36 of relay IKa, back contact I31 of relay IJ, front contact I38 of relay IBI, front contact I39 of relay ICI and winding of relay IL to terminal C. Relay IL therefore becomes energized and is subsequently held in its energized condition until the conclusion of the control code by virtue of a stick circuit which passes from terminal B, over front contact 296 of relay IK, front contact I36 of relay IKa, front contact I60 of relay IL, and winding of relay IL to terminal C. At the end of the first impulse of the control code, relay IR becomes energized, and relay IJ then picks up. Relay IBIa also becomes energized and relay IBI releases. At the beginning of the second impulse of the code, relay IR becomes de-energized, picking up relay IE2 and releasing relay IBIa. As previously described,- the second impulse of the control code is long, and during this long impulse, relay IJ releases. When this happens, a pick-up circuit is completed for group selector relay IG from terminal B, over back contact I4I of relay IBI, front contact I42 of relay IB2, jumper I63, front contact I64 of relay ICI, back contact M5 of relay IJ, front contact I46 of relay ICI, and winding of relay IG to terminal C. Relay IG thereupon becomes energized and is subsequently held in its energized condition until the conclusion of the control code by virtue of a stick circuit which passes from terminal B, over front contact 296 of relay IK, front contact I36 of relay IKa, front contact I61 of relay IG and winding of relay IG to terminal C. Of course, the line relays IR at each of the other stations operate in synchronism with relay IR and this second long impulse of the code picks up the group selector relay corresponding to relay IG at stations 2, 3 and 4, as well as at station No. 1. At the conclusion of the third impulse, relay IR again becomes energized to pick up relay IJ and als-o relay IBM. The third impulse causes relay I B3 to become energized and releases relay IBZa. This impulse is short, however, and relay IJ does not release. In similar manner the fourth impulse is short and relay IJ does not release during this impulse. At the beginning of the fifth impulse, however, relays IC2 and IBI become energized and since this fifth impulse is long, relay I J releases, whereupon, a pick-up circuit is completed for the station relay S at only one of the stations which have their group selector relays energized. In the present instance the station relay is picked up at station No. l, the circuit passing from terminal B, over front contact I II of relay IBI, jumper I48, front contact I49 of relay ICZ, back contact I45 of relay IJ, front contact I50 of relay ICE, front contact I5I of relay IG, and winding of relay IS to terminal C. Relay IS is subsequently held upuntil the conclusion of the control code by virtue of a stick circuit which passes from terminal B, over front contact 296 of relay IK, front contact I36 of relay IKa, front contact I52 of relay IS and winding of relay IS to terminal C.

The sixth, seventh, eighth and ninth impulses are all short and accomplish nothing at station No. 1, except to step along the'counting relay chains so that when the tenthi-mpulse is received, relays IE2 and IC3 are energized. This tenth impulse is long and relay IJ therefore releases. When this happens, current flows from terminal B, over front contact 296 of relay IK, front contact I36 of relay IKa, back contact I31 of relay IJ, front contact I53 of relay IS, front contact I54 of relay I03 front contact I55 of relay IE2, and winding of relay IF2 to terminal C. Relay IF2 is subsequently stuck up over a circuit including its own front contact I56 and front contacts 296 and I36 of relays IX and IKa, respectively. At the conclusion of the tenth impulse, the closing of relay IR again picks up relay IJ. The eleventh impulse is short so that relay IJ does not become'de-energized during this impulse. The twelfth impulse is long, however, and during this impulse relay IJ releases while relays IE4 and IC3 are energized. A pick-up circuit is then completed for relay "IF I from terminal B, over front contact 296 of relay IK, front contact I36 of relay IKa, back contact I31 of relay IJ, front contact I53 of relay IS, front contact I54 of relay IC3, front contact 6 I51 of relay IB4, the winding of relay IF4 to terminal C. Relay IF4 is subsequently maintained in its energized condition until 'the'conclusion of the control code by a stick circuit which includes its own front contact I58 and front contacts 296 and I36'of relays IK and IKa, respectively. At the end of the twelfth impulse, the energization of relay IR picks up relay IJ and also of course, picks up relay IC3a. and drops relays I'C3 and IE4. When relay IR becomes de-energize'd'at the beginning of the thirteenth impulse, relay IC4 becomes energized, relay IC3a releases, and relay IBI is energized. The thirteenth impulse is the final or delivery impulse of the control code and during this long impulse, relay IJ becomes deenergized, and current B, over front contact 296 of relay IK, front contact I36 of relay IKa, back contact I31 of relay IJ, front contact I38 of relay IBI, front contact I59 of relay IS, front contact I66 of relay IC4, front contact I6I of relay IL, and winding of relay IF5 to terminal C. Relay IF5 is subsequently stuck up over its own front contact I63 and front contacts 296 and l36of relays IK and IKa, respectively. When relay IF5 becomes energized, it breaks the stick circuit for switch control relays INWS at back contact I69 of relay IF5. The switch control relay INWS is therefore de-energized. The operation of relay IF5, however, completes a pick-up circuit for relay IRWS from terminal B, over contact 5 of the dual selector'mechanism of switch 3, normal contact I64 of key release is, front contact I65 of relay I of relay IFI, front contact I61 of relay IE2, front contact I68 of relay IV, winding of relay IRWS and contact 30 of thermo-sensitive relay M to terminal C. The closing of relay IF5 also breaks the stick circuit forrelay ILH at back contact I14 of relay IF5, and relay ILI-I releases. A pick-up circuit is now closed, however, for relay IRH from terminal B, over contact 5 of the dual selector mechanism of switch 3, normal contact I64 of key release is, front contact I14 of relay IF5, back contact I15 of relay IF3, front contact I16 of relay IF4 and winding of relay IRH to terminal C. e

During. the thirteenth impulse, relay IC4 is energized and front contact I62 of this relay is then then flows from terminal IF5, back contact I66 connected in parallel with front contact I36 of relay IKa. Relays IF2, IF4 and IF5 are therefore held in their energized condition independently of relay IKa. At the conclusion of the thirteenth impulse, relay IR picks up, and relays IJ and IKw are then energized consecutively and relay IBIa picks up and relay IBI releases. Since relay IR remains closed, relay IK is, of course, de-energized and at the conclusion of its holding interval, relay IK releases, thereby de-energizing relays IBIa, IC4, IL, IG, IS, IF2, IF4 and IF5. With the apparatus in. this condition the equipment at station No. 1 is prepared to receive another code. When relay IK releases, it also decnergizes relay IJ. When relay IJ releases, it de-energizes relay IKa, and when relay IKw releases, the starting circuit is prepared to start the transmission of an indication code as will be explained hereinafter.

When relay IRWS picks up it opens the control circuit for the indication relay IKR, so that the latter relay becomes de-energized, thereby opening the circuit for any signal control relay which may happen to be energized. In the present instance, relay ILAH becomes de-energized, there-- by restoring signal ILA to the stop position. Since all signals now occupy the stop position, relay IX becomes energized. The closing of front contact 25 of relay IX completes the pick-up circuit previously traced for the contactor IRW, over front contact 28 of relay IRWS, and the motor m is operated to reverse switch 3 as described hereinbefore. When the switch has attained its full reverse position, contactor IRW opens, and indication relay IKR becomes energized in the'reverse direction. Since relay IRH is now energized and relay IKR is energized in the reverse direction, a circuit is completed for signal control relay IRBH, so that relay becomes energized and completes the operating circuit for signal IRB, to clear the signal.

It should be noted that when relay IF5 became energized, during the final impulse of the control code, relay IHD became energized over front contact I83 of relay IF5 so that relay iI-ID is now energized, a stick circuit for the relay passing over its own front contact I85 and back contact I84 of relay IF8.

It should also be observed that when relay IF5 became de-energized at the conclusion of the final impulse of the control code, stick circuits were completed for relays IRWS and IRH, the stick circuit for relay IRWS passing from terminal B, over contact 5 of the dual selector mechanism of switch 3, front contact I64 of key release lc,'back contact I65 of relay IF5, front-contact I19 of relay IRWS, winding of relay IRWS and contact 38 of thermo-sensitive relay hI t terminal C. The stick circuit for relay IRH may be traced from terminal B, over contact operated by dual selector mechanism of switch 3, front contact I64 of key release is, back contact I14 of relay IF5, back contact I82 of relay ILH, front contact I8I of relay IRH and winding of relay IRH to terminal C.

I will next assume that the operator wishes to leave switch 3 at station No. 1 in its reverse position, but wishes to clear eastbound signal ILB instead of the westbound signal IRB' over this route. In order to accomplish this, he leaves the switch control lever Ip on panel No. 1 at the office in its reverse or right-hand position and moves the signal control lever lg to its left-hand position. In order to initiate the transmission to the line circuit of a control code corresponding to the positions now occupied by the levers on panel No. 1, he operates the starting button OPI. The equipment at the ofiicecperates to deliver a control code to the line circuit in the manner previously described, and the code has the same characteristics as the code described in detail hereinbefore except that the eleventh impulse of the code is long instead of the twelfth impulse. This is accomplished in the following manner.

At the beginning of the eleventh impulse, relays 033 and 003 at the ofiice are energized, and under these conditions a holding circuit is completed for relay OT which passes from terminal B on Fig. l of the drawings, through back contact 91 of relay OBI, back contact 93 of relay 032, front contact 99 of relay 0B3, signal control lever Iq on panel No. 1 in its left-hand position, front contact I34 of relay OSI, front contact I33 of relay 003, front contact I I2 of relay OJP, front contact I I3 of relay OT, front contact IUI of relay OM, and winding of relay OT to terminal C. The circuit just traced holds relay OT energized after relay 0B3 picks up to break the pick-up circuit for relay OT until relays OJ and OJP release consecutively. When front contact II2 of relay OJP opens, the holding circuit just traced is interrupted and the relay OT becomes de-energized to restore the line circuit and terminate the eleventh impulse. During the twelfth impulse no holding circuit is completed for relay OT, so this impulse is short. In all other respects, the operation of the apparatus at the despatchers oflice is the same as previously described and the code signal then supplied to the line circuit contains I3 impulses of which the first, second, fifth, tenth, eleventh, and thirteenth are long and the remaining impulses are short.

Referring now to the apparatus at station No. 1, when the code last described is received at the station, the operation of the equipment is the same as described hereinbefore except that during the eleventh impulse, relay IF3 is energized in the following manner:

At the beginning of the eleventh impulse, relays IB3 and I03 are both energized, and since this impulse is long, relay IJ becomes de-energized and a circuit is completed from terminal B, over front contact 296 of relay IK, front contact I35 of relay IKit, back contact I31 of relay IJ, front contact I53 of relay IS, front contact I54 of relay IC3, front contact 29'! of relay IE3, and Winding of relay IF3 to terminal C'. Relay IF3 is subsequently held in its energized condition by virtue of a stick circuit including its own front contact I8! and front contacts 296 and I36 of relays IK and IKa. Since the twelfth impulse of the control code now supplied to the line circuit is short, relay I F4 does not become energized.

Under the conditions just described, when the final or delivery impulse of the control code is received, and relay IF5 becomes energized, current is supplied from terminal B, over contact 5 operated by the dual selector mechanism of switch 3, front contact I64 of key release is, front contact I'M of relay IFS, back contact I'II of relay IE4, front contact N8 of relay IF3, and winding of relay ILH to terminal C. Relay ILH therefore becomesenergized and the opening of back contact I'M of relay IFS opens the stick circuit for relay IRI-I and allows the latter relay to release. When relay IF5 again becomes de-energized a stick circuit is completed for relay ILH including its own front contact I I9,

back contact I80 of relay [RH and back contact I14 of relay IF5.

It should also be observed that when the control code was received, the stick circuit for relay IRWS, which is now assumed to be energized was interrupted by the opening of back contact I55 of relay IF5. When relay IF5 operated, however, relay IFZ was energized and the pick-up circuit for relay IRWS was closed through back contact I66 of relay IFI and front contact I61 of relay IFZ, so that when relay IF5 again becomes de-energized, the stick circuit for relay IRWS continues to energize this relay and no change is made in the control of the switch 3. When relay IRH became de-energized, the circuit for relay IRBI-I was openend so that signal IRB was restored to the stop position. Since relay ILH is now energized and since relay IKR is energized in the reverse direction, relay ILBH now picks up, thereby completing the operating circuit for clearing signal ILB to permit the passage of westbound trafiic over switch 3 in its reverse direction.

I will next assume that the operator wishes to restore the switch 3 at station No. 1 to its normal position, and to clear the signal for westbound traffic over the switch in its new position. In order to accomplish this result, he leaves the signal control lever I q on panel No. 1 in its left-hand position and moves the switch control lever In to its normal or left-hand position. He then operates the starting button OPI, whereupon, the apparatus at the ofiice transmits to the line circuit a control code similar to the control codes previously described and having its first, second, fifth, ninth, eleventh and thirteenth impulses long and the remaining impulses short. The operation of the equipment at the office for prolonging the eleventh impulse has already been described and I will now describe the holding circuit for prolonging the ninth impulse to accomplish the restoration of the switch 3 at station No. 1 to its normal position. At the beginning of the ninth impulse, relays OBI and 003 at the office are energized, relay OT having been energized by its normal pick-up circuit over back contacts of the counting relays OBI, 032, etc. This pick-up circuit was opened when relay OBI became energized, but a holding circuit is now completed for relay OT from terminal B, through front contact 91 of relay OBI,

switch control lever Ip in its normal or left-hand position, front contact 295 of relay OSI, front contact I33 of relay 003, front contact II2 of relay OJP, front contact II3 of relay OT, front contact IIII of relay OM and winding of relay OT to terminal C. Relay OT is therefore held energized to prolong the ninth impulse, until relays OJ and OJP release consecutively. When relay OJP opens its front contact I I 2, the holding circuit for relay OT is interrupted and that relay releases to restore the line circuit and to termimate the ninth impulse. During the tenth impulse, no holding circuit is completed for relay OT, so that impulse is short.

Referring now to the equipment at station No. 1, when the control code, having its first, second, fifth, ninth, eleventh and thirteenth impulses prolonged, is received at station No. 1, the operation of the apparatus is similar to that previously described except that relays IFI, IF3 and three long impulses. The operating circuits of relays IF3 and IF5 have been described hereinbefore, and the pick-up circuit for relay IFI passes from terminal B, through front contact IF5 are energized by the last 296 of relay IK, from contact I36 of relay IKa, back contact I31 of relay IJ, front contact I38 of relay IBI, front contact I59 of relay IS, front contact I88 of relay I03 and winding of relay IFI to terminal C. Relay IFI is energized over the circuit just traced following the de-energization of relay IJ during the long ninth impulse of the control code and is subsequently stuck up over its own front contact I89 and front contacts of relays IK and IKa. It is assumed that previous to the reception of the control code just described, relay IRWS was energized. When relay IF5 becomes energized at the conclusion of the code, the stick circuit for relay IRWS is interrupted, and that relay releases. At the same time, the closing of front contact I69 of relay IFS completes a circuit from terminal B, through contact 5 operated by dual selector mechanism of switch 3, contact I64 of key release k, front contact I69 of relay IF5, back contact III of relay IFZ, front contact I12 of relay IFI, front contact I13 of relay IV, winding of relay INWS and contact of thermo-sensitive relay 712 to terminal C. Relay INWS therefore becomes energized, and when relay IFS again becomes de-energized a stick circuit is completed for relay INWS over its own front contact I86 and back contact I69 of relay IF5. The opening of relay IRWS de-energizes the indication relay IKE, thereby de-energizing any signal control relay and placing all signals at stop. With the signals all in stop position, relay IX is energized and current then flows over front contact of relay INWS to pick up contactor INW. Motor m is then operated, as previously described,

to restore switch 3 to its normal position, whereupon the contactor INW is de-energized and the indication relay IKR becomes energized in its normal direction. a

When relay IF5 became energized during the final impulse of the control code, the stick circuit for relay ILH was interrupted, but the pickup circuit was completed for relay ILH during the time interval that relay I F5 was energized, so that when relay IF5 again closes its back contact, relay ILH is held in its energized condition. When relay IKR becomes energized, then, relay I LAI-I becomes energized and signal ILA is cleared.

I will next assume that the operator wishes to place all of the signals at station No. 1 at stop without affecting the, position of switch 3., In order to do this, he moves the signal control lever id to its middle position, leaving the switchcontrol lever Ip in whichever position it happens to occupy, and operates the starting button OPI. The control code then delivered to the line circuit has both the eleventh and twelfth impulses short, as will be plain from the foregoing without tracing the operation in detail. When this code is received at station No. 1, the operation of, relay IFS during the final impulse of the code, deenergizes eitherof the directional control relays ILH or IRH which may have been energized and these relays both remain deenergized when relay IF5 again closes its back contacts. Under these conditions, then, all the signal control relays are deenergized and the signals all indicate stop.

It will be plain, from the foregoing that the ninth and tenth impulses in each control code are allocated to the control of the switch at a station, the ninth impulse being prolonged to operate the switch to its normal position and the tenth im pulse being prolonged to operate the switch to its reverse position. In similar manner, the e1evefi11h and twelfth impulses of the control code are allocated to the control'of the signal at each station, the, eleventh impulse being prolonged to clear the 'westboundsignals, and the twelfth impulse being prolonged to clear the eastbound signals. In any case, the only signal that can be picked up by the control code and the circuits are so arranged that it is impossible to clear a signal over a route different from that intended, as a result of a failure of a relay or an omission of an element'in the code already due to failure of the switch to operate. it should be noted that since the indication relay IKR, is controlled not only by the switch circuit controller contacts 9 and I0 but also by contacts of relays INWS and IRWS, no signal can be In this latter connection,

cleared unless the switch ocupies the position corresponding to the route set up by the condition of relays INWS and IRWS.

In all of the preceding discussion, I have consideredv only the transmission of control codes from the despatchers office to station No. 1, and

it will be manifest that each of these codes has the first impulse long and also the second and fifth impulses long to pick up relays IL, IG and I S .at'station No. 1. From an inspection of the drawings, Fig. 3, it will be plain that relay IG is energized by a long second impulse in the code because jumper I43 connects front contact I44 of relay ICI with front contact I42 of relay I B2. Had jumper I43 connected front contact I44 of relay ICI with front contact I90 of relay IE3, it

would have been necessary to prolong the third impulse of the control code in order to pick up relay IG. Similarly, had the jumper I43 been adjusted to connect front contact I44 of relay ICI with front contact I9I of relayIB4, relay IG could be energized only if the fourth impulse of the control code were long. Furthermore, by proper adjustment of jumper I48, the apparatus could be arranged to pick up relay IS on codes having the sixth, seventh or eighth impulses long instead of the fifth impulse, as shown in the drawings, by connecting jumper I48 to a corresponding contact of the counting relay chain. It ,is apparent from the foregoing that the apparatus at the station can be adjusted to respond to any one of twelve different combinations of long impulses in the code and each station will be selected only by the code having the proper combination of long impulses. Since none of the apparatus at a station can be actuated in response to a .control code unless the station relay at that station corresponding to relay IS at station No. 1 has been energized, it follows that the station will be unaffected byanycode except the one intended .for that station, and of course, in

practice the jumpers I43 and I48 at each of the 12 stations will be adjusted so that each station will respond to a different code.

If a code is to be sent from the despatchers ofli'ce for controlling apparatus at a station other than station No. 1, it may be accomplished by operating apparatus associated with the panel corresponding to such station in the same manner as already described in connection with panel No. 1 at the despatchers oflice, the equipment including a set of 12 panels when there are 12 stations to be controlled. In addition. each of the 12 main control panels may be provided with an approach panel, such as is illustrated in the drawings associated'with panel No. 1, for the purpose of giving the operator additional information which he can not obtain from the main control panel. It will be seen that starting relay OH! determines, when energized, that the second and fifth impulses of the control code shall belong. If, however, the individual starting relay for a different panel is energized, other impulses are prolonged to select the corresponding station. At the despatchers office the selection between impulses is accomplished by the group of contacts illustrated at the bottom of Fig. 2, where I have shown the starting relays for all of the l2 panels, although the operating circuits of these relays have been omitted from the drawings for the sake of simplicity. Each of these starting relays controls the selection of its own panel and station in a manner similar to that described for the selection of panel No. l and station No. 1 by the operation of relay OHI.

At each station, the delivery relay F5 energized by the final impulse of the code, requires for its operation that the lock-out relay for that station shall have been energized by the first impulse of the code. For example, at station No. 1, relay lF5 can not be energized during the thirteenth impulse of a control code unless the lock-out relay IL is energized. Relay IL becomes energized only if the first impulse of the control code is a long impulse, and this arrangement prevents im proper operation of the station delivery relay by an indication code originating at one of the other stations, which indication codes, as will be explained hereinafter, always have the first impulse short.

In the apparatus located at station No. 1, the circuits provide cross-checks between the functions operated by the ninth and tenth impulses, and between the functions operated by the eleventh and twelfth impulses. For example, if the ninth impulseis long to move the switch to its normal position, the apparatus will not operate unless the tenth impulse is short, and similar cross-protection is given between the eleventh and twelfth impulses.

The operator at the despatchers ofiice may operate several starting buttons in rapid succession and the corresponding control codes will be sent out consecutively and in order. It is therefore possible for an operator having charge of, a number of stations to set up a route involving all of these stations, and operate all of the starting buttons. No further action onv the part of the operator is necessary, the equipment functioning automatically to deliver the proper control codes to position the apparatus at the several control stations in accordance with the positions of the levers on the panels at the despatchers office.

The apparatus is also arranged to transmit, from each station, indication codes similar to the control codesfor operating indication means at the despatchers ofiice in response to any change in the condition of the apparatus located at the: station. Each. indication code gives complete information to the operator concerning the condition of all apparatus at the station at the time that the indication code is transmitted. For the particular system here illustrated, each indication code consists of 16 impulses of which the first is a locking impulse and is always short as distinguished from the long impulse which invariably commences a control code. The next seven impulses in each indication code are utilized to select, at the despatchers ofiice, the panel which corresponds with the station at which the indication code originates. The ninth to the fifteenth impulses in each indication code are used to select indication relays associated with the panel corresponding to the station transmitting the code. The final or sixteenth impulse of the code is prolonged, as in control codes, and serves to actuate the relays controlling the indication lamps and other apparatus associated with the panel in accordance with the condition of the indication relays at the selected panel.

The ninth and tenth impulses are allocated to switch indication, the ninth impulse being long to indicate switch normal and the tenth impulse being long to indicate switch reverse. The twelfth impulse indicates the condition of an approach section adjacent the switch controlled from the main panel, the parts being so arranged that an approach indication lamp on the approach. panel associated with the main control panel is lighted when the twelfth impulse is long, but is extinguished if the last indication code received by the panel had a short twelfth impulse. In similar manner the eleventh impulse controls the track indication informing the despatcher of the condition of the track section containing the switch. Thus the lamp 8! on panel No. l is lighted if the last indication code received from station No. 1 had a long eleventh impulse, but this lamp is extinguished if the eleventh impulse was short in the last indication code received from station No. 1. The thirteenth, fourteenth and fifteenth impulses in each indication code are utilized to give information concerning both the signals and the track section at the station. The thirteenth impulse is long and the fourteenth and fifteenth impulses are short if the westbound signal is cleared. If all signals are at stop and the section containing the switch is unoccupied the thirteenth and fifteenth impulses are short and the fourteenth impulse is long. If an eastbound signal is clear the thirteenth and fourteenth impulses are short and the fifteenth impulse is long. The thirteenth,

fourteenth and fifteenth impulses are all short if the signals are all at stop and the track section is occupied.

The equipment at any station may be set into operation under a number of conditions. The operation of the equipment to transmit an indication code from a station is initiated by energizing the associated master relay M and this takes place- 1. Following a change in position of the track relay, as by the entrance of a train into the switch track section.

2. Following a change in position of the approach relay (relay ILAA at station No. 1) as by the entrance of a train into the corresponding approach section.

3. Following the reception of any control code from the despatchers office.

4. Following a change in position of any signal from clear to stop, or vice-versa, not resulting from the reception of the control code or the entrance of a train into the switch track section.

5. Following an operation of the dual selector mechanism of the switch at the station.

In explaining the operation of the apparatus in transmitting an indication code from station No.1 to the dispatchers ofiice, I will assume that ,contact 2III2IJ I closes.

picks up relay the apparatus at the station occupies the condition in which it is illustrated in the drawings, that is, switch 3 is normal, the section bis unoccupied, and signal ILA is clear. I will now assume that a train enters section bthereby tie-energizing track relay ITR. For purposes of simplicity, I will assume that this train is wholly within the limits of section b -f so that all approach relays IRA, ILBA and ILAA are energized. The opening of front contact II of relay ITR de-energizes relay ITP, and also opens the operating circuits for all signals at front contact I92 of relay ITR (bottom of Fig. 4) so that all signals indicate stop. Relay IX therefore becomes energized, and relay ITK is energized over back contact I93 of relay ITP. Relay ITK is subsequently maintained in its energized condition by virtue of a stick circuit including its own front contact I94 and back contact I95 of relay ITD.

Relays ITD and ITK control a starting circuit for the code transmitting equipment at station No. 1 which is normally open when these relays are in agreement but is arranged to be closed when either relay is energized if the other relay is de-energized. Under the -present'conditions, then, the starting circuit is closed, from terminal 13, over front contact I96 of relay ITK, back contact I91 of relay ITD, back contact I93 of relay II-ID, back contact I99 of relay IK, back contact 208 of relay IKa. and winding of relay IM to terminal C. It will be plain that the circuit just traced is closed only if relays IK and IKa are both deenergized,-so that this circuit is held open if a code is being transmitted over the line circuit. Assuming. however. that the line circuit is clear. relay IM becomes energized. When this happens. contact 20 I-2Il I opens. and

This operation. of relay IM disconnects the portion of the line circuit beyond station. No. 1 and closes the line ,circuit, between station No. l and the despatchers oflice, through a resistance 202 so proportioned as to compensate for the portion of the line circuit which. is disconnected. It will also be noted that the line circuit to the despatchers office now includes back contact 203 of transmitting .relay IT. Under these conditions, all line stations beyond the transmitting station are locked out so that these stations do not receive the in.- dieation code being sent to the despatchers office.

nor can one of these stations take possession of the line to interfere with the code being sent to the despatchers ofiice.

When relay IM picks up, a pick-up circuit is completed for relay IT similar to the pick-u circuit previously described in connection with the transmitting relay OT at the despatchers office, and passing from terminal B. over back contact I4I of relay IBI, back contact I42 of relay IBZ, back contact I 90 of relay IB3, back contact IBI of relay IB4, front contact 294 of relay IM, and winding of relay IT to terminal C. Relay IT therefore becomes energized. opening the line circuit and releasing the line relay IR at the sending station together with the line relays at the 'despatchers oflice and at any stations located between station No. 1 and the despatchers office. At station No. 1, when relay IR releases, it operates the counting chain, as described in connection with the despatchers office. That is to say, the release of relay IR first IJ and relay ICI. When relay IJ picks up, relays IBI and IKa become energized and the closing of relay IBI completes a circuit for relay IK. When relay IK picks up, relay IJ is .de-energized but this relay does not release during the first impulse of the indication code. When relay IBI becomes energized, it opens the pick-up circuit for relay IT at back contact I4I of relay IBI and relay IT releases to close back contact 283- and restore the line circuit to terminate the first impulse. It will be noted that the pick-up circuit for relay IM was opened when relay IKa picked up, but a holding circuit for relay IM is now closed from terminal B, over front contact 296 of relay IK, back contact 205 of relay IL, front contact 2% of relay IM, front contact 2% of relay IKa, and winding of relay IM to terminal 0. This holding circuit maintains relay 'IM energized until the transmission of the indication code has been completed. It

will be noted that this first impulse of the code is short so that relay IJ does not become energized and relay IL remains de-energized.

When relay IT releases, following the energization of relay IBI, relay IR becomes energized, thereby energizing relay IJ and picking up relay IBIa. Relay IBI then releases and closes the pick-up circuit for relay IT to open the line circuit and start the second impulse of the indication code. When relay IR opens, relay I132 becomes energized and relay IBIa releases. The energization of relay I132 interrupts the pick-up circuit for relay IT but this relay is now held energized by a holding circuit which passes from terminal B, over back contact I4I of relay IBI, front contact I42 of relay IE2, jumper I43, front contact I44 of relay ICI, front contact I45 of relay IJ, front contact 20? of relay IT, front contact 284 of relay iIlVIand winding of relay IT to terminal C. Relay IT is therefore energized until relay IJ releases. Relay IJ became file-energized when relay IR released at the beginning of the second impulse, and at the conclusion of the holding time of relay IJ, this relay releases, thereby opening the holding circuit just traced for relay'IT, and de-energizing the latter relay. When relay IT releases it restores the line circuit to terminate the second impulse.

When relay IJ releases; however, during the second impulse, the closing of backcontact I45 of this relay completes a pick-up circuit for relay IG whichis the same as the holding circuit for relay IT as far as contact I45 of relay IJ, and passes thence over front contact I45 of relay I CI and winding of relay IG to terminal C. Relay IG is subsequently held up over its stick circuit including its own front contact 'I4'I and contacts 296 and I36 of relays IK and IKa. The length of the second impulse is measured by the consecutive release of relays IJ and IT. This long impulse is therefore equal to approximately 24 cycles.

At the conclusion of the second impulse, relay IR picks up and energizes relays IJ and IBM. The operation'of the equipment during the third and fourth impulses, which are short impulses, will be apparent from the foregoing without tracing the circuits in detail. At the beginning of the fifth impulse, however, relays ICZ and IBI become energized and the pick-up circuit for relay IT is then interrupted. A holding circuit is now closed for relay IT, however, from terminal B, over front contact I4I of relay IBI, jumper I48, front contact I49 of relay IC2, front contact I45 of relay IJ, front-contact 2M of relay IT, front contact 204 of relay IM, and winding of relay IT to terminal C. Due to this holding circuit, the relay IT is held energized to keep the line circuit open until relays IJ and IT release consecutively thereby prolonging the fifth impulse to approximately 24 cycles. When relay IJ releases, a circuit is completed for relay IS which is the same as the holding circuit just traced for relay IT as far as back contact I45 of relay IJ and passes thence over front contact I50 of relay ICZ, front contact IEI of relay IG and winding of relay IS to terminal C. Relay IS therefore becomes energized and is subsequently stuck up over its own front contact I52 and front contacts 296 and I36 of relays IK and IKa. When relay IT releases to terminate the fifth impulse, the counting relays are again set into operation and the equipment continues to function during the sixth, seventh and eighth impulses to transmit three short impulses to the line circuit. When relay IR becomes de-energized at the beginning of the ninth impulse, relays IBI and IC3 are energized. A holding circuit is now completed for relay IT for prolonging this impulse to give a switch normal indication at the despatchers oflice. This holding circuit passes from terminal B over front contact 208 of relay IKR, normal contact 209 of relay IKR, front contact 210 of relay IBI, front contact 2 of relay IC3, front contact I45 of relay IJ, front contact 207 of relay IT, front contact 204 of relay IM and winding of relay IT toterminal C. This holding circuit maintains relay IT energized until relay IJ releases, whereupon relay IT releases and the line circuit is restored to terminate the ninth impulse. When relay IJ releases, however, a pick-up circuit is completed for relay IF! from terminal B, over front contact 296 of relay IK, front contact I36 of relay lKa, back contact I 31 of relay IJ, front contact I38 of relay IBI, front contact I59 of relay IS, front contact I 88 of relay IC3, and Winding of relay IFI to terminal C. Relay IFI is subsequently held up by a stick circuit over its own front contact I89 and front contacts 296 and I36 of relays IK and IKa. When relay IT closes its back contact 203 at the end of the long ninth impulse, relay IR becomes energized and picks up relay ,IBIa. Relay IBI then releases to close its back contact MI and complete the pick-up circuit for relay IT to start the tenth impulse. When relay IR releases, relay IE2 becomes energized andrelay IBIa releases. There is no holding circuit for relay IT during the tenth impulse so that the energization of relay IBZ de-energizes relay IT, and when this relay releases it restores the line circuit to terminate the tenth impulse, which is therefore short. Relay IR therefore again becomes energized, picking up relay IBM, and relay IBZ releases to close its back contact I42 and energize the pick-up circuit for relay IT, thereby opening the line circuit to start the eleventh impulse. When relay IR releases, relay IB3 picks up and relay IBZa releases. The eleventh impulse is prolonged to give an occupied track indication at the despatchers office, and to accomplish this result a holding circuit is now completed for relay IT from terminal B, over front contact 2I2 of relay ITK, front contact 2I3 of relay IB3, front contact ZII of relay I03, front contact I45 of relay IJ, front contact 20'! of relay IT, front contact 264 of relay IM, and winding of relay iT to terminal 0. This holding circuit maintains relay IT energized until relay IJ releases, whereupon relay IT releases and restores the line circuit to terminate the eleventh impulse. When relay IJ releases, a pick-up circuit is completed for relay I F3 from terminal B,

over front contact 296 of relay IK, front contact winding of relay IF3 to terminal C. Relay IF3 is subsequently held energized over a stick circuit including its own front contact and front contacts 296 and I36 of relays IK and IKa.

The twelfth, thirteenth, fourteenth and fifteenth impulses of the indication code are short and these impulses are produced by operation of the apparatus in a manner similar to that heretofore described and readily understood from the drawings without tracing the operation of the apparatus in detail.

The sixteenth impulse is the delivery impulse, and at the beginning of this impulse, relay IR releases to pick up relay IE4 and release relay IB3a. Relay I04 is now energized and a holding circuit is therefore closed for relay IT which does not include a contact of relay IJ but may be traced from terminal B, over back contact I4I of relay IBI, back contact I42 of relay IBZ, back contact I90 of relay IB3, front contact I9I of relay IE4, front contact 2I4 of relay IC4, front 5 front contact ZI'I of relay IB4. When relay IF8 {30 becomes energized, a pick-up circuit for relay ITD is completed over front contact ZI8 of relay IF8, and front contact 2I9 of relay IF3. The energization of relay ITD interrupts the stick circuit for relay ITK so that relay I TK is now controlled solely by relay ITP. It follows that if relay ITP had become energized as a result of the train leaving section b-f before the indication code was completed, relay ITK would have been held up over back contact I of relay ITD to complete the track occupied code, but relay ITK would release at the completion of the code and this operation would then start the transmission of a new indication code to report this change of condition to the despatchers office.

During the long sixteenth impulse, relay IJ is of course de-energized and when it releases, it de-energizes relay IKa. When relay IKa releases it de-energizes relay IM and when relay IM releases, it closes back contact 20 I2Il I to terminate the sixteenth impulse and restore the line circuit through the stations more remote from the despatchers office. As a result, relay IR then picks up to terminate the sixteenth impulse which in theindication code is thus measured by the consecutive release of relays I J, I Ka and IM and is equal to opproximately 45 cycles. The opening of relay IMreleases relay IT which thereupon becomes de-energized, and the opening of relay IM also de-energizes relay I F8, which thereupon releases and completes a stick circuit for relay I TD including back contact 2I8 of relay IFB, front contact 220 of relay ITD. Relay ITD is held energized in agreement with relay ITK which is now energized by its pick-up circuit because relay ITP is assumed to be de-energized as a result of the presence of a train in section b). Relay ITD remains energized until an indication code, is transmitted which does not contain the occupied track indication, that is, a long eleventh impulse.

When relay IR becomes energized, at the end of the sixteenth impulse, relays IJ and IKa pick up consecutively and relay IB4 releases, but since relay IT is not now connected in the line circuit, 

